Manqin Guan, Zhihao Li, Wenxiu Liu, Hui Wang, Jun Zhao, Zihang Wang, Jintao Geng, Xiaodong Zhang
Semiconductor-based photocatalysis enables high-value organic chemical synthesis, whereas the role of photocatalyst-substrate interactions in regulating excited-state properties and catalytic performance has long been neglected. Herein, we propose designing ionic active sites in polymeric carbon nitride (CN) to strengthen catalyst-Selectfluor bonding for promoting photocatalytic Selectfluor activation. We demonstrate that light-induced potassium release exposes negatively charged bridging nitrogen sites in semicrystalline cyanamide-functionalized potassium-doped carbon nitride (K-CN), which could accommodate the cation species of Selectfluor. The notable K-CN-Selectfluor interaction results in the formation of charge-transfer states, endowing the system with notable visible-light response and effective electron transfer. Besides, semicrystallinity-related exciton dissociation and cyanamide-group-related electron trapping synergistically promote Selectfluor activation. Benefiting from these features, K-CN exhibits excellent activity in triggering benzylic C‒H fluorination. Taking ethylbenzene fluorination for example, K-CN gave a 1-fluoroethylbenzene yield rate of ∼47.5 mmol g- 1 h- 1, which is 47 times higher than pristine CN.